Context. To understand the important health risks they face and whether they can do anything to reduce these risks, people need data that is intrinsically quantitative and probabalistic. Unfortunately, there is evidence that people have trouble with the basic skills required to understand such data: working with probabilities, recognizing the additional information needed to give probability meaning, and making basic assessments about data quality. Objectives: * To develop and evaluate a general education booklet to help people think about and make use of numbers in health. Tentatively entitled, Understanding Numbers in Health, the booklet will cover the following areas: risk, what to look for in statements about risk, how to put cancer risk and treatment benefit in perspective, how to make sense of changes in risk, and quality of evidence. * To facilitate the communication of data by putting risk into context, we will develop and evaluate 3 basic risk communication tools to supplement the tutorial: Cancer risk charts: tables containing age-specific mortality rates for a range of diseases plus all-cause mortality. Prevention benefit charts: tables presenting the mortality benefit of various preventive strategies. Standard disease summary templates: a standard format to present information about a specific disease. Methods. Development Phase. Iterative review process of draft materials with content experts in the fields of education mathematics, epidemiology and genetics to ensure that the material is accurate and clearly articulated. Pilot testing (debriefing interviews for understandability) in two populations most likely to benefit from the tutorial: people with low numeracy and people currently concerned about the screening or treatment of cancer (i.e., cancer genetic testing, cancer treatment decisions, and women undergoing screening mammography). Evaluation Phase. We plan to conduct a formal evaluation of the tutorial and risk communication tools using a before-after study design (immediate and longer-term follow up at 3 months). The sample will be drawn from the same two populations as in the development phase. The primary outcome measure will be critical reading skills of medical data (i.e., ability to make use of data). Secondary measures will include comfort working with numbers, attention to medical data and ratings of materials for usability and satisfaction. Significance. This project is the groundwork for a body of research testing the effect of general education in a range of patient decisions from whether to undergo genetic testing for cancer susceptibility to choosing among health plans based on their report cards.